Melanoma incidence and Breslow tumour thickness development in the central Alpine region of South Tyrol from 1998 to 2012: a population-based study.

BACKGROUND

Cutaneous melanoma incidence is increasing worldwide, especially for in situ and thin (<1 mm) lesions, while thick (≥1 mm) lesions have been generally stable in many studies; although epidemiological data on melanoma is readily available, population-based studies, especially on mountain regions, are rare.

OBJECTIVE

The aim of this study was to analyse cutaneous melanoma incidence and Breslow tumour thickness in the central Alpine mountain region of South Tyrol, northern Italy.

METHODS

All newly diagnosed cutaneous in situ and invasive melanomas in the resident population from 1998 to 2012 were taken from the Pathology Unit, Bolzano Hospital and South Tyrol Cancer Registry. Incidence and Breslow tumour thickness were analyzed. Statistical analyses included Mann-Whitney and Kruskal-Wallis tests.

RESULTS

A total of 784 in situ melanomas and 1663 invasive melanomas were collected. In situ melanomas showed the highest increase: European age-standardized incidence rose from 2.44 per 100,000 inhabitants in 1998-2002 to 16.01 in 2008-2012. Invasive melanoma incidence increased from 12.69 in 1998-2002, to 22.88 in 2008-2012. The incidence rise was observed in thin melanomas (from 8.39 to 16.18) and in thick melanomas (from 4.30 to 6.70). Breslow distribution revealed a median value of 0.62 mm (mean 1.34; SD 2.24; range 0.09-30.0) and did not change significantly over time (P = 0.286). Higher Breslow values were observed at advanced age (P < 0.001), among males (P = 0.017), in nodular melanomas (P < 0.001) and at higher Clark levels (P < 0.001). Significant differences were also found in urban hospitals compared to rural hospitals during the whole period (P = 0.004), but not in the last 5 years (P = 0.053).

CONCLUSION

Incidence of cutaneous melanoma is increasing in South Tyrol, especially for in situ and thin lesions, but also for thick lesions; no reduction in median tumour thickness is observed. Rural areas and elevated altitudes may contribute to this effect.